Sighting apparatus for guns.



i ,mgdhb. 7211M y ggr A. T. DAWSON 82; G. TLBUCKHAM. SIGHTING APPARATUS FOR GUNS. APPLICATION FILED FEB. 29. 1908.

905,798. Patented Dec, 1,1908.

2 SHEETSSHEET 1.

A. T. DAWSONAz G.- T. BUGKHAM.

SIGHTING APPARATUS FOR GUNS..

APPLIOATION FILED FEB. 29. 1908.

Patented Dec. 1, 1908.

2 sums-sum 2.

UNirEn STATES PATENT .oEEroE.

ARTHUR TREVOR DAWSON AND GEORGE THOMAS BUOKHAM, OF WESTMINSTER, LONDON, ENGLAND, ASSIGNORS TO VIOKERS SONS & MAXIM LIMITED, OF LONDON, ENGLAND.

SIGHTING- APPARATUSZFOR GUNS.

Original application filed June 1, 1907, Serial No. 376,813.

Specification of Letters Patent.

Serial No. 418,416.

To all whom it may concern:

Be it known that we, ARTHUR TREVOR DAWSON, lieutenant Royal Navy, director and superintendent of ordnance works, and GEORGE THOMAS BUOKHAM, engineer, both subjects of the King of Great Britain, residing at 32 Victoria street, Westminster, in the county of London, England, have invented certain new and useful Improvements in Sighting Apparatus for Guns, of which the following is a specification.

This invention relates to sighting apparatus for guns, and has for its chief object to enable corrections to be made in the sighting in order to compensate for the variations that arise from the fall in muzzle velocity due to repeated firing of the gun and also those that arise from differences in the temperature of the charges resulting from the climatic conditions, as regards heat and cold, which prevail at different parts of the globe.

The principle upon which our apparatus is constructed is that the alteration in the range for a given elevation of the gun is pro portional to the alteration in muzzle velocity and also to the variation of the normal temperature of the charges. For instance at a given elevation of the gun the decrease in range, due to a diminution of a given number of foot-seconds, is approximately twice that which is due to a diminution of half that number of foot-seconds.

For the purpose of our invention we employ in conjunction with the range dial a cam Which by means of suitable gearing receives motion from the range dial and is adapted to transmit angular movement to the range pointer through the intervention of suitable mechanism which is capable of being set to compensate for the aforesaid variations in the muzzle velocity and the temperature of the charges.

According to our invention, when applied to sighting apparatus of the kind in which a spirally grooved range dial and a radially movable pointer are employed, the cam is adapted to make one complete revolution for the maximum elevation of the sight and is adapted to act, through the intervention of a roller, upon a lever which is capable of rocking about a suitable pivot. The said guide in which the aforesaid pointer moves by the action of the spiral groove in the dial is adapted to receive angular displacement muzzle velocity and the temperature corv rections.

In order that our said invention may be clearly understood and readily carried into effect we will describe the same more fully with reference to the accompanying drawings, in which Figure l is a front elevation of our improved apparatus applied to sighting apparatus of the kind above stated. Fig. 2 is a vertical section of the same. Fig. 3 is a front elevation showing a modification in which two of the cams are employed for actuating the aforesaid lever instead of one as shown in Figs. 1 and 2. Fig. 4 is a section taken approximately on the line 22 of Fig. 3.

A is the range dial, and A its graduated spiral groove. B is the radially movable pointer that engages with the said spiral groove in the well known manner and B is the guide in which said pointer moves during the revolution of the dial. O is the cam, D the lever actuated thereby, and E the pivot about which said lever rocks when thus actuated.

According to the construction of the apparatus shown by Figs. 1 and 2, the aforesaid range dial A has teeth a on its perip ery gearing with a toothed pinion a mounted on an axle c which is carried by the dial frame or other suitable stationary part of the apparatus. The said axle a has a worm a which gears with a worm wheel a carried by a spindle a This spindle is mounted in bearings a a on the dial frame and carries the cam O which is arranged with its axis transverse to the axis of rotation of the range dial, so that it presents the appearance of a wide cam or roller. Below this wide cam is the lever D bearing a graduated scale, and movable about a stationary ivot E. Lines representing the various fa ls in muzzle velocity are marked on this graduated scale, and on these muzzle velocity lines, points are marked to represent charge-temperatures.

The pivoted lever or graduated scale D carries the adjustable temperature slide 6, which is movable horizontally, that is to say lengthwise with respect to the said wide cam C. This temperature slide also carries the muzzle velocity slide e which is movable vertically, that is to say towards and away from the said wide cam.

On the back of the temperature slide and movable therewith is the roller D which is carried in a hinged bearing so as to permit it to lie wholly in contact with the aforesaid wide cam at all the angles which the pivoted lever D assumes. Forming part of or made in one with the said pivoted lever D is a toothed sector (V which participates in the angular movements of the pivoted lever and which gears with teeth b onthe pointerguide B, so that the said guide and its pointer will be angularly displaced about the axis of revolution of the range dial according to the setting of the temperature and range slides on the graduated lever D. Therefore the nearer the temperature slide 6 is shifted along the lever D towards the pivot E, the greater will be the angular movement imparted to the toothed sector (1*, when the wide cam C is actuated; consequently the said guide B and its pointer will travel through the angle necessary to give correction due to variation in muzzle velocity and temperature, when the aforesaid slides 6 e have been set to their respective marks. When the gun is being fired with the maximum muzzle velocity and with a charge at the normal temperature, the slide 6 will be moved into a position in which its roller lies clear of the wide cam C, in which case the guide B and its pointer will not be moved by the toothed sector d there being no correction necessary under such circumstances. d is a spring for keeping the said pivoted lever and the roller D in contact with the wide cam C. Obviously the aforesaid gearing for transmitting motion from the range dial to the wide cam may be varied without de arting from the nature of our invention.

n the further modified arrangement illustrated in Figs. 3 and 4:, two of the aforesaid wide cams C are employed, one situated above and the other below the roller D. These cams are connected with the teeth a of the range dial by means of toothed pinions a and worm gearing a a as already explained in connection with the last preceding arrangement and the said cams are so arranged that as they move, the throw of one increases in proportion as the throw of the other diminishes. The said lever D is thus rocked about its pivot E in either direction by a positive action of the cams on the roller, so that the use of a spring such as cZ used in the last preceding arrangement can be dispensed with, and unintentional movement of the lever from any position to which it is set by the said cams, is avoided.

Although we have described ourinvention with particular reference to sighting apparatus in which a spirally grooved range dial and radially movable pointer are employed we wish it to be understood that the said invention is applicable to other forms of sighting apparatus in which a range dial and displaceable pointer are employed.

NVhat we claim and desire to secure'by Letters Patent of the United States is 1. In gun sighting apparatus, the combination with the range dial and its pointer, of a cam operating in conjunction with the range dial and having its axis disposed transversely with respect to the axis of the range dial, mechanism for transmitting angular motion to the pointer from the cam, and means for enabling said mechanism to be set to compensate for variations in shooting due to atmospheric influence and to changes in the muzzle velocity.

2. In gun sighting apparatus, the combination with the range dial and its pointer, of a cam operating in conjunction with the range dial, and having its axis disposed transversely withrespect to the axis of the range dial, a lever for transmitting angular motion to the pointer from the cam, and means for varying the degree of .movement transmitted by said lever from the cam to the pointer.

3. In gun sighting apparatus, the combination with the range dial and its pointer, of a cam operating in conjunction with the range dial, and having its axis disposed transversely with respect to the axis of the range dial, a lever for transmitting angular motion to the pointer from the cam, and means for varying the amplitude of movement of said lever about its fulcrum.

4. In gun sighting apparatus, the combination with the range dial and its pointer, of a cam operating in conjunction with the range dial and having its axis disposed transversely with respect to the axis of the range dial, a bent or bell-crank lever mounted on a stationary pivot with one of its members movable in a plane parallel to that of the range dial, a slide adjustable on said member with respect to suitable scales thereon, a roller carried by the adjustable slide, means for keeping the latter in contact with the cam in all positions to which the slide is set, and gearing connecting the other member of said bell-crank lever with the pointer.

5. In gun sighting apparatus, the combination with the range dial and its pointer, of a pair of cams operating in conjunction with the range dial and'having their axes disposed transversely with respect to the axis of the range dial, a bent or bell-crank lever mounted on a stationary pivot with one of its members movable in a plane parallel to that of the range dial, a slide adjustable on said member With respect to set our hands in presence of two subscribing suitable scales thereon, a roller carried by Witnesses this 13th day of December 1907.

the adjustable slide in a position between the ARTHUR TREVOR DAWSON.

said pair of cams, and gearing connecting GEORGE THOMAS BUCKHAM. 5 the other member of said bell-crank lever WVitnesses:

with the pointer. HENRY KING,

In testimony whereof We have hereunto l C. A. SEARLE. 

